Droplet actuators are used to conduct a wide variety of droplet operations, such as droplet transport and droplet dispensing. A droplet actuator typically includes two surfaces separated by a gap. One or both surfaces include electrodes for conducting droplet operations. The gap typically includes one or more filler fluids that are relatively immiscible with the droplets. Droplets may, for example, be reagents and/or droplet fluids for conducting assays. In wide variety of applications, such as the production of antibodies and assaying stem cells, samples within droplet actuators may include cells to be manipulated and, therefore, there is a need for new approaches to manipulating cells within a droplet actuator.